The central aim of the proposed research is to study the ontogenesis of the facial expressions of emotions during the first two years of life. The seven stimulus situations for obtaining an objective emotion expression ontogeny are acute pain (inoculations), separation, stranger approach, visual cliff, novel sights, sounds, and play. Our second aim is to relate the emergence, peaking, and regulation of particular emotion expressions in the selected stimulus situations to specific cognitive attainments and play behaviors. The final aim is to investigate the relationship between certain demographic and emotion-related measures of the mothers on the one hand and developmental changes in their infants' emotion expressions and emotion-cognition relationships on the other. The infant's facial behavior and the infant-other interactions in the stimulus situations will be videotape recorded, with one camera zoomed on the infant's face and another camera shooting the whole scene. Using a synchronous dual-monitor playback system with a frame-by-frame control, analysis of the infant's facial expressions (camera 1 data) will be related to his/her vocal, visual, postural-gestural, and motor behavior (camera 2 data), to scores on specific cognitive tasks, and to demographic data and such data as the mother's perception of expressions and her attribution of emotion to the infant.